Colorectal carcinoma is the third leading cause of death in the United States. Fluoropyrimidine therapy has been the mainstay of treatment for patients with advance disease. Regimens which combine 5-Fluorouracil (5-FU) plus le ucovorin have routinely demonstrated higher response rate in 5-Fluorouracil alone. UFTb(Uracil and Ftorafur) has demonstrated to be equally efficacious as 5-Fluorouracil and Leucovorin with different toxicity profile. There is little to no data, however, which compares the pharmacokinetics profile of this drug in patients from the United States versus a Japan population. This a limited institution, international trial which will treat patients with advance colorectal cancer with UFT plus leucovorin with blood sampling for pharmacokinetics as well as monitoring for toxicity and object response as well as survival. This trial is part of a registration trial for this drug in Japan, but more importantly will provide unique information regarding racial differences in drug metabolism.